Engine exhaust device

Abstract

An engine exhaust device includes: a first catalyst; a second catalyst; and a tubular connecting member. The connecting member includes: a first opening; a second opening; and a bend connecting. A downstream end surface of the first catalyst is connected to the first opening, and an upstream end surface of the second catalyst is connected to the second opening. The downstream end surface and the upstream end surface form a dihedral angle within a range from 60 to 120 degrees. A part of the upstream end surface of the second catalyst includes an overlap that is close and opposed to a part of a surface of the first catalyst. The bend of the connecting member includes: a first wall; a second wall; and a connector. The first wall has a curve. The curvature radius of the first wall is greater than the predetermined curvature radius.

The invention claimed is: 
     
       1. An engine exhaust device, comprising:
 a first catalyst disposed in an exhaust passage of an engine to purify exhaust gas discharged from the engine; 
 a second catalyst disposed downstream of the first catalyst in a direction of a flow of the exhaust gas to purify the exhaust gas that has passed through the first catalyst; and 
 a tubular connecting member forming a part of the exhaust passage, and connecting the first catalyst to the second catalyst, wherein 
 the connecting member includes:
 a first opening located upstream in the flow of the exhaust gas; 
 a second opening located downstream in the flow of the exhaust gas; and 
 a bend connecting the first opening to the second opening, 
 
 a downstream end surface of the first catalyst is connected to the first opening, 
 an upstream end surface of the second catalyst is connected to the second opening, 
 the downstream end surface of the first catalyst and the upstream end surface of the second catalyst form a dihedral angle within a range from 60 to 120 degrees, 
 a part of the upstream end surface of the second catalyst includes an overlap that is close and opposed to a part of a surface of the first catalyst, 
 the bend of the connecting member includes:
 a first wall opposed to the downstream end surface of the first catalyst; and 
 a second wall opposed to the upstream end surface of the second catalyst; 
 the first wall is connected to the second wall with a predetermined curvature radius, 
 
 the first wall has a curve curving with a curvature radius from at least one of a top and bottom of the connecting member along an outer periphery of the second catalyst, when viewed from the second opening with the first opening arranged on a right side or a left side, 
 the first wall being configured to direct the exhaust gas along an inner radial surface portion of the first wall, and 
 the curvature radius of the first wall is greater than the predetermined curvature radius. 
 
     
     
       2. The device of  claim 1 , wherein
 the first catalyst is inserted into the connecting member from the downstream end surface of the first catalyst through the first opening, and 
 the second catalyst is inserted into the connecting member from the upstream end surface of the second catalyst through the second opening. 
 
     
     
       3. The device of  claim 2 , wherein
 a central axis of the first catalyst is located below a plane which includes a central axis of the second catalyst and is parallel to the central axis of the first catalyst, and 
 the curve is formed near a bottom of the connecting member. 
 
     
     
       4. The device of  claim 3 , further comprising:
 an exhaust manifold disposed above and close to the first catalyst, wherein 
 the bottom of the connecting member and a bottom of the second catalyst are formed linearly so that a vehicle component is placed below and close to the bottom of the connecting member and the bottom of the second catalyst. 
 
     
     
       5. The device of  claim 3 , wherein
 a base for mounting a NO x  sensor is provided on a top of the connecting member. 
 
     
     
       6. The device of  claim 1 , wherein
 the connecting member includes:
 a first connecting member provided with the first opening and a part of the second opening; and 
 a second connecting member provided with the other part of the second opening, wherein 
 
 the first wall and the second wall are provided in the second connecting member. 
 
     
     
       7. The device of  claim 4 , wherein
 a base for mounting a NO x  sensor is provided on a top of the connecting member. 
 
     
     
       8. The device of  claim 2 , wherein
 the connecting member includes:
 a first connecting member provided with the first opening and a part of the second opening; and 
 a second connecting member provided with the other part of the second opening, wherein 
 
 the first wall and the second wall are provided in the second connecting member. 
 
     
     
       9. The device of  claim 3 , wherein
 the connecting member includes:
 a first connecting member provided with the first opening and a part of the second opening; and 
 a second connecting member provided with the other part of the second opening, wherein 
 
 the first wall and the second wall are provided in the second connecting member. 
 
     
     
       10. The device of  claim 4 , wherein
 the connecting member includes:
 a first connecting member provided with the first opening and a part of the second opening; and 
 a second connecting member provided with the other part of the second opening, wherein 
 
 the first wall and the second wall are provided in the second connecting member. 
 
     
     
       11. The device of  claim 5 , wherein
 the connecting member includes:
 a first connecting member provided with the first opening and a part of the second opening; and 
 a second connecting member provided with the other part of the second opening, wherein 
 
 the first wall and the second wall are provided in the second connecting member. 
 
     
     
       12. The device of  claim 1 , wherein
 the first wall includes a wall transition, a wall slope, and a wall step, the wall transition extends forward from a downstream end where the second opening is formed, 
 the wall slope is connected to the wall transition and extends toward the first catalyst, 
 the wall step has a rear portion connected to the wall slope and a front portion connected to the second wall, 
 the wall transition is part of the curve and has a curvature radius as the curvature radius of the first wall, and 
 the wall step is part of the curve and has a curvature radius as the curvature radius of the first wall. 
 
     
     
       13. The device of  claim 12 , wherein
 the curvature radius of the wall transition is greater than the curvature radius of the wall step. 
 
     
     
       14. The device of  claim 1 , wherein
 the curve generates a flow of the exhaust gas that reaches the first wall and winds up into a space between the first catalyst and the second catalyst.